Onyx 4.6.6 Custom Tool Secret Header Disclosure via Tool Endpoints

Advisories

Onyx 4.6.6 Custom Tool Secret Header Disclosure via Tool Endpoints

severity: high
date: 9/4/2026
Affecting: onyx <= 4.6.6
CVE: CVE-2026-85700
CWE: CWE-522 Insufficiently Protected Credentials
CVSS: 7.1
CVSS V4 Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
References: GitHub Issue #13165
https://github.com/onyx-dot-app/onyx
https://github.com/onyx-dot-app/onyx/blob/v4.6.6/backend/onyx/server/features/tool/models.py
https://github.com/onyx-dot-app/onyx/blob/v4.6.6/backend/onyx/server/features/tool/api.py
Credit: George Chen
Description: Onyx 4.6.6 fails to properly restrict access to custom tool credentials stored in custom_headers, allowing any authenticated user to read admin-defined API keys. Attackers with basic authentication can call GET /tool/{tool_id} or GET /tool endpoints to retrieve plaintext authorization headers and third-party API credentials, then use them to directly access upstream APIs.

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